This study will compare two groups of subjects with complex abdominal aortic aneurysms. It will compare their clinical outcomes and quality of life measures. The group being treated in this study will have their aneurysms repaired by an endovascular approach using Zenith® Fenestrated AAA Endovascular Graft. This group will be compared to a group of 461 patients (historical cohort) whose complex aneurysms were treated by open surgical repair.